1. Field of the Invention
The present invention relates to a powder coating composition which is employed for coating an automobile, a building material or a metal product.
2. Description of the Background Art
Acrylic resin powder coating material is watched with interest in view of the excellent appearance of a coating film as formed, weather resistance, solvent resistance, flexibility and the like. Powder coating material which is applied as a clear coating or the like is known as an acrylic resin powder coating material. For example, each of Japanese Patent Publication Nos. 53-15089 (1978), 58-4947 (1983) and 58-25388 (1983) discloses acrylic resin powder coating material prepared from acrylic resin containing glycidyl groups, which is heat-cured after coating.
Such acrylic resin powder coating material is baked at a temperature of 160.degree. to 180.degree. C. after coating, although it is preferred that the coating film be formed by baking the coating material at a lower temperature of 130.degree. to 160.degree. C., in consideration of productivity and energy savings. When conventional acrylic resin powder coating material is baked at such a low temperature, however, the appearance of the coating film is deteriorated with reduction in weather resistance and blocking resistance. While it may be possible to add a curing catalyst to the coating material for facilitating curing at a low temperature, storage stability is deteriorated in this case.